The World War II is the most deadly war in Human History with over 80 million casualties. This number was equal to %3-%5 of world population of estimated as 2 billion. War lasted 6 years between 1939 and 1945. Area of the WW II can be accepted as all over the world. Around 30 counties including all super power countries had involved to war and lost people and lived pain. There were two main sides of this conflict Allies side and Axis side. Main actors of Axis side were Nazi Germany, Italy and Japan. On the other side; main actors of Allies were USA, Soviet Union, France, UK, rest of the European countries. Almost every crime against humanity committed in these cursed years. Atomic bomb was used for the first time by USA in Japan. Thousands of people, maybe million, were died and affected by two atomic bombs. Radioactive effects of atomic bombs had affected people of Japan. Mass deaths of civilians occurred many times including the Holocaust. Many people starved and many butchered after torture. The start of the war can be considered as the Invasion of Poland by Hitler. Two events ended the war Capture of Berlin by Soviet Union and surrender of Japan after atomic bombs. There are many results of this violent war. The United Union was established. The main powers of the Allies are accepted as the permanent members of UN Security Council : USA, China, Russia, France, UK. The main purpose of the foundation of UN was to prevent future armed conflicts. Another important result of the war is Cold War between two super powers USA and Soviet Union.